Generally, this kind of side-pull type caliper brake, as disclosed in the Japanese Utility Model Laid-Open Gazette No. Sho 60-192,992 and as shown in FIG. 5, is provided with; a pair of brake arms D and E having brake shoes A and operating portions B and C respectively; a fixing member I having a pivot shaft F and a support arm H disposed at one radial side of the pivot shaft F and extending reversely to the operating portions B and C, one of the brake arms D and E being pivoted to the pivot shaft F and the other to the support arm H; and an association mechanism K having an adjusting screw bolt J and disposed between the brake arms D and E.
In the conventional side-pull type caliper brake, as shown in FIG. 5, a line 1 connecting the pivot point 0.sub.1 for one brake arm D pivoted to the pivot shaft F and that 0.sub.2 for the other brake arm pivoted to the support arm H is horizontal, and the axis m of adjusting screw bolt J at the association mechanism K is positioned at the lengthwise center of and perpendicularly to the line 1 so as to apply equivalent operating forces to the brake arms D and E.
In a case where the side-pull type caliper brake constructed as above-mentioned is mounted on a bicycle, especially on the front wheel side thereof, since bicycle equipments, such as, a reflector, a front basket and a head lamp, are mounted on the front wheel side, the adjusting screw bolt J is positioned in a relatively restricted space between the bicycle frame and the equipments mounted thereon, and a rotary operating portion j at the adjusting screw bolt J is disposed in the restricted space in a manner of orienting vertically upwardly. As a result, the adjusting screw bolt J, when operated to adjust the associaiton relation between both the brake arms D and E, must be rotated from just above, thereby creating the problem in that the adjusting screw bolt J is difficult to operate.
Also, at the aforesaid side-pull type caliper brake, return springs (not shown in FIG. 5) are interposed between the fixing member I and the respective brake arms D and E.
Therefore, when a control wire W fixed to the operating portion C is pulled for the braking action, a spring force of a return spring for biasing the brake arm D at the driven side is smaller, or reduced because of being rusted after the use or mudded, thereby creating the problem in that the respective arms are not associated in operation with each other and the brake arm at the driven side operates in advance of that at the driving side to cause the one-sided braking effect.